A kind of two-way isolated DC converter
Technical field
The present invention relates to a kind of DC converter of field of power electronics, specifically relate to a kind of two-way isolated DC converter.
Background technology
In the AC system, power model comprises the H full-bridge, three-phase bridge, and power model connection in series-parallel technology is increasingly mature.The chain type converter generally adopts the mode of power model AC side series connection to improve voltage withstand class, and the chain type converter has been widely used in high-pressure frequency-conversion, reactive power compensation field at present; Power model parallel-connection multiple technology then is widely used in the various occasions of the big capacity current transformer of needs, as locomotive transmission, active power filtering field.
The DC-DC converter is that a kind of direct current is transformed to the galvanic technology of another kind of form, mainly voltage, electric current is realized conversion.Usually the DC-DC converter all is one-way only operation, and it is unidirectional that main cause is that its power switch is, so energy can only one-way flow.Yet in many application scenarios, the DC-DC converter needs two-way flow.Topology based on bidirectional DC-DC converter, it is divided into non-isolation type and isolated form topological structure again, DC-DC converter for non-isolation type, though can satisfy the application demand of different capacity grade, and satisfy the application of low pressure, big electric current, but voltage conversion ratio is little, and the DC-DC converter of isolated form can be realized required voltage large velocity ratio.And the DC-DC converter of isolated form is divided into two anti-swash topology, topological, the two half-bridge topology of double push-pull and the bridge topologys of enjoying a double blessing.
All the time, the development of the development of direct current transportation and commutation technique (particularly high voltage, high-power converter) has confidential relation.But in recent years; except progressive promotion that power electronic technology is arranged; because putting into operation of a large amount of DC engineering; various problems such as the control of direct current transportation, protection, fault, reliability also seem important all the more, so the integrated application of new technologies and methods makes the direct current transportation technology that new development arranged.
Summary of the invention
The purpose of this invention is to provide a kind of two-way isolated DC converter, this two-way isolated DC converter is realized straight-friendship-straight power converter, can be applicable to carry out in the system of DC converting; Two-way isolated DC converter forward can be finished the transfer process from the high direct voltage to the dc low-voltage, oppositely can finish the transfer process from the dc low-voltage to the high direct voltage, has realized the two-way flow of energy.
Purpose of the present invention adopts following technical proposals to be achieved:
A kind of two-way isolated DC converter, its improvements are that described converter is connected in the direct current system, and described converter is connected to form by the modular converter of at least one; Described modular converter comprises that two power models are DC/AC module and AC/DC module; The AC side of described DC/AC module and AC/DC module is connected by transformer T; The DC side of described DC/AC module and AC/DC module is shunt capacitor C1 and C2 respectively; The DC side of described DC/AC module is together in series and constitutes the high direct voltage side; The DC side of described AC/DC module is together in series or parallel and constitutes the dc low-voltage side.
A kind of optimized technical scheme provided by the invention is: described power model is the circuit of H bridge form or is used for rectification or the circuit of the converter form of inversion.
Second optimized technical scheme provided by the invention is: the brachium pontis of described H bridge comprises turn-off device, diode and electric capacity in parallel successively; Described turn-off device is the full control power electronic device of IGBT, IGCT, GTO or power MOSFET.
The 3rd optimized technical scheme provided by the invention is: the power model on described transformer T both sides is symmetry or asymmetric version.
The 4th optimized technical scheme provided by the invention is: the DC side series, parallel of described AC/DC module or connection in series-parallel are in conjunction with constituting the dc low-voltage side.
Compared with prior art, the beneficial effect that reaches of the present invention is:
1, two-way isolated DC converter energy provided by the invention can flow to the right side from the left side, also can flow to the left side from the right side, and energy is one-way flow or two-way flow on converter; Can realize boosting, decompression transformation;
2, two-way isolated DC converter provided by the invention is realized high voltage, big electric capacity by the series and parallel combination of DC side;
3, the transformer of two-way isolated DC converter AC side provided by the invention has the Fault Isolation function, and when a side of converter is short-circuited or earth fault, fault coverage can not expand opposite side to;
4, two-way isolated DC converter provided by the invention can be used for wind-powered electricity generation, solar energy photovoltaic direct current inserts occasion; Also can be used for direct current microgrid application scenario;
5, the power model of two-way isolated DC converter provided by the invention is provided with overvoltage protection, can in time protect power model itself and storage capacitor, prevents fault;
6, two-way isolated DC converter provided by the invention need adopt applicability current-sharing/equal flow problem of Pressure and Control strategy processing topology in parallel and series connection topology all to press problem.
Description of drawings
Fig. 1 is the complete schematic of two-way isolated DC converter;
Fig. 2 is the fundamental diagram of two-way isolated DC converter;
Fig. 3 is the two-way isolated DC converter H bridge topological diagram of giving an example;
Fig. 4 is two-way isolated DC converter cascade structure topological diagram;
Fig. 5 is two-way isolated DC converter H bridge cascade structure low-pressure side parallel-connection structure figure;
Fig. 6 is two-way isolated DC converter H bridge cascade structure low-pressure side tandem junction composition;
Fig. 7 is that the specific embodiment of both sides provided by the invention module symmetry is connected to 1kV direct current system topological diagram for the 10kV direct current system;
Fig. 8 is that module asymmetric specific embodiment in both sides provided by the invention is connected to 10kV direct current system topological diagram for the 35kV direct current system.
Embodiment
Below in conjunction with the drawings and specific embodiments the specific embodiment of the present invention is described in further detail.
Fig. 1 is the complete schematic of two-way isolated DC converter, and converter is connected to form by the modular converter of at least one; Modular converter comprises that two power models are DC/AC module and AC/DC module; The AC side of DC/AC module and AC/DC module is connected by transformer T; The DC side of DC/AC module and AC/DC module is shunt capacitor C1 and C2 respectively; The DC side of DC/AC module is together in series and constitutes the high direct voltage side; The DC side of AC/DC module is together in series or parallel and constitutes the dc low-voltage side.
Fig. 2 is the fundamental diagram of two-way isolated DC converter, shown in Fig. 2 (a), is the operation principle topological diagram of two-way isolated DC converter, and transformer T primary side voltage is represented with Vab; The secondary side voltage of transformer T is represented with Vcd; The electric current to secondary side of transformer primary side is represented with IL; Shown in Fig. 2 (b), be the oscillogram of voltage Vab, Vcd and electric current I L, its energy Flow direction is that high side to low side flows; Present principles figure is equally applicable to energy and flows to the high-pressure side from low-pressure side.
Fig. 3 is the two-way isolated DC converter H bridge topological diagram of giving an example, and power model is the circuit of H bridge form; The brachium pontis of H bridge comprises turn-off device, diode and electric capacity in parallel successively; Turn-off device is the full control power electronic device of IGBT, IGCT, GTO or power MOSFET; The power model on transformer T both sides is symmetry or asymmetric version.
Fig. 4 is two-way isolated DC converter cascade structure topological diagram; Two-way isolation DC-DC converter basic principle provided by the invention is that AC side connects by transformer by full-bridge H bridge current transformer, realizes buffer action, and DC side inserts the two ends direct current system separately, realizes the connection of two direct current systems.
Fig. 5 is the topology diagram of specific embodiment of the invention low-pressure side power model parallel connection; Insulated gate pole bipolar transistor IGBT, integrated gate commutated thyristor IGCT, gate turn off thyristor GTO and power MOSFET tube controlled the through-flow restriction of power electronic device entirely, in order to realize to high-power applications, employing is at series connection of dc low-voltage side and the topological structure that combines in parallel, total current equals all parallel connection converter electric current sums, by increasing module number in parallel, can realize high-power converter.
Fig. 6 is the topology diagram of specific embodiment of the invention low-pressure side power model series connection; Insulated gate pole bipolar transistor IGBT, integrated gate commutated thyristor IGCT, gate turn off thyristor GTO and power MOSFET tube controlled the withstand voltage restriction of power electronic device (turn-off device) entirely, in order to realize to high voltage applications, adopt the topological structure of power model in the series connection of high direct voltage side, total voltage equals all current transformer direct voltage sums, by increasing series connection power model quantity, can realize general applicability to the direct voltage grade.
As illustrated in Figures 5 and 6, the individual power model of left side N (2 to 33) by the series connection of power model DC side, constitutes the high direct voltage side, and high side voltage equals each module direct voltage sum; As illustrated in Figures 5 and 6, the individual power model of right side N (2 to 33) connects and composes the dc low-voltage side by power model DC side serial or parallel connection, and low-pressure side voltage equates with module series connection quantity voltage sum.
The apply in a flexible way number of series and parallel power model, the withstand voltage and through-current capability of choose reasonable turn-off device can be designed the DC converter at the different application occasion.
The present invention is described in further detail below in conjunction with specific embodiment.
Embodiment 1
Fig. 7 is that the specific embodiment of both sides provided by the invention module symmetry is connected to 1kV direct current system topological diagram for the 10kV direct current system; For the 10kV direct current system is connected on the 1kV direct current system, the full control power electronic device of each H brachium pontis adopts the IGBT of 1700V/800A;
Right side dc low-voltage side power model is all in parallel, and it is withstand voltage that each H bridge all can reach 1kV, so electric current can reach 400A and multiply by 10, about 4000A;
Left side high direct voltage side needs 10 H bridges to adopt series system in order to realize being directly connected to the 10kV direct current system, and each H bridge is all pressed 1kV, high voltage side current 400A like this;
Such system, can be applicable to two the cover direct current systems interconnected, transmitted power can reach 4MW.
Such scheme can be applied in permanent magnet direct-drive blower fan wind power generation direct current and insert in the network system:
As land wind-powered electricity generation: high side voltage: 10kV, low-pressure side voltage: 1000V~1100V (electric current 1200A~5000A), power: 1.2MW~5MW.Bi-directional power conversion.The course of work: high pressure → low pressure: charging; Low pressure → high pressure: generating.
Embodiment 2
Fig. 8 is that module asymmetric specific embodiment in both sides provided by the invention is connected to 10kV direct current system topological diagram for the 35kV direct current system; Take all factors into consideration the function and the protection of DC converter, the full control power electronic device of each H brachium pontis of left side adopts the IGBT of 6500V/400A; The full control power electronic device of each H brachium pontis of right side adopts the IGBT of 1700V/800A;
Left side DC side power model needs to adopt 10 H bridge series systems because system voltage is higher, and each H bridge is all pressed 3.5kV like this, left-sided system electric current 100A;
Right side DC side power model is all connected, and it is withstand voltage that each H bridge all can reach 1kV, because power conservation, its right side electric current can reach 350A;
Such system can be applicable to two cover direct current microgrid system interconnect, and transmitted power can reach 3.5MW.
Should be noted that at last: only illustrate that in conjunction with the foregoing description technical scheme of the present invention is not intended to limit.Those of ordinary skill in the field are to be understood that: those skilled in the art can make amendment or are equal to replacement the specific embodiment of the present invention, but these modifications or change are all among the claim protection range that application is awaited the reply.